KEY FACTS
Terminology
- •
Mature cystic teratoma (MCT) = dermoid cyst
- •
Immature teratoma
- •
Monodermal teratoma in which 1 cell line predominates
Imaging
- •
MCTs have variety of appearances
- ○
Heterogeneous cystic ovarian mass with echogenic shadowing mural nodule (Rokitansky nodule) on US
- ○
± fat-fluid level
- ○
Highly echogenic focus/foci with distal acoustic shadowing represent teeth
- ○
Hair within sebum creates characteristic dot-dash-dot appearance
- ○
- •
Fat-containing adnexal mass is diagnostic on CT
Top Differential Diagnoses
- •
Hemorrhagic cyst
- •
Endometrioma
- •
Bowel
Pathology
- •
Mature tissues of endodermal, mesodermal, and ectodermal origin
- •
88% unilocular, fat content liquid at body temperature, semisolid at room temperature
Clinical Issues
- •
Most common ovarian tumor
- •
10-20% bilateral
- •
Rarely undergo malignant degeneration
- •
Rupture in < 1% of cases
- •
May act as lead point for adnexal torsion
Scanning Tips
- •
If dermoid is predominately echogenic in appearance due to predominantly fatty contents, it may mimic bowel and may be difficult to appreciate on transvaginal imaging; these are often better seen on transabdominal view
. The echogenic shadowing Rokitansky nodule 
along the periphery is diagnostic for a dermoid.
and echogenic fluid content 
. A peripheral Rokitansky nodule 
is present as well.
within the dissected mature cystic teratoma. Hair 
arises from nodule.
, which is present in ~ 1/3 of cases. Notice the fat 
within the dermoid is markedly hypodense even compared to normal extraperitoneal fat 
.
. It is usually echogenic and often causes distal acoustic shadowing.
within a mature cystic teratoma. Fat is liquid at body temperature but semisolid at room temperature.
